What Currier found
A WWII codebreaker, working by hand, spotted a pattern that has held up for fifty years.
Two styles, not one
Currier noticed that some pages were written in a neat, widely spaced hand, and others in a tighter, more slanted one. To his eye, two different people were writing. The statistical behavior of the text tracked that visual split.
Different endings and frequencies
Certain word endings are common in "B" and almost absent in "A." Some symbol groups repeat heavily in "A" and rarely in "B." The two sections are each internally regular, but follow different rules from one another.
"Languages," in quotes
Currier was careful: he called them "languages" but stressed they need not be different languages at all. They could be dialects, subject matter, or different conventions. The label stuck; the caution often gets dropped.
Two hands, by the numbers
Currier worked by hand. With modern methods the split can be measured precisely, and reproduced by anyone.
What it does, and doesn't, mean
A measured difference is not the same as a reading.
A single uniform stream
The manuscript is not one homogeneous text. Whatever it is, it was produced under at least two distinct regimes, a fact any successful theory has to explain.
Why they differ
Two scribes, two topics, two stages of an evolving system, or two encodings would all produce a split like this. The data alone does not yet decide between them. Later paleography (Lisa Fagin Davis) finds as many as five distinct scribal hands.
Any meaning
Measuring that A and B differ says nothing about what either one says. We characterize the structure. We do not claim to read it.